Flu (Influenza) Vaccine

What is the flu (influenza)?

Influenza (flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The flu is different from a cold. The flu usually comes on suddenly. People who have the flu often experience fever, chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue (tiredness). Some people may have vomiting and diarrhea, though this is more common in children than adults.

Some people, such as people over age 65, young children, and those with certain health conditions, are at high risk for serious flu complications. The best way to prevent the flu is by getting vaccinated each year with a flu shot.

What is the flu shot?

The "flu shot" is a vaccine that protects you from the flu virus. It is inactivated, which means it contains a killed version of the virus which cannot cause disease, and is most commonly given as an injection (with a needle) in the arm.

This season's vaccine protects against three or four influenza viruses that research indicates will be most common during the season. This includes an influenza A (H1N1) virus, an influenza A (H3N2) virus, and 1 or 2 influenza B viruses.

The vaccine takes effect approximately two weeks after it has been administered as antibodies (substances in the blood that protect against infection) accumulate and provide protection against influenza. Therefore, it is important to get a flu vaccine before the flu begins to circulate in your area as you may be susceptible to influenza during the two weeks after your flu shot.

The flu shot will not eliminate the risk of getting the flu 100% as there are several strains of viruses that can cause the flu. However, data suggests flu symptoms may be milder and complications can be reduced following vaccination. It can also protect others who are vulnerable but may not be able to receive the vaccine for a variety of reasons.

Is there a Flu Vaccine for age 65+?

Seniors ages 65 and older have a higher risk for developing complications from the flu and account for more than 60% of the flu-related hospitalizations each year. Recent studies show that people ages 65+ may not respond as well to standard-dose flu shots because they do not produce as high of an antibody response following vaccination as do younger people. People with low antibody levels may be at higher risk of catching the flu.

There are vaccines, such as Fluzone High-Dose and FLUAD, designed specifically for patients ages 65+ and works by improving the production of antibodies in order to provide a stronger immune response to the flu than traditional vaccines. Like the standard flu shot, these vaccines are given as an injection in the arm and the side effects are similar, though some patients may experience increased pain, redness, or swelling around the injection site compared to standard dose flu vaccines.

Who should get a flu shot?

The CDC recommends everyone ages 6 months and older* get a flu shot every flu season, including healthy people, and people with chronic conditions. In general, it is recommended that anyone who wants to reduce his or her chances of getting the flu should be vaccinated. It's especially important for some people to get vaccinated, including:

  • People who are at high risk of developing serious complications like pneumonia if they get sick with the flu. This includes:
    • People who have certain medical conditions including asthma, diabetes, and chronic heart or lung disease
    • Pregnant women
    • People 65 years and older
    • People who live with or care for others who are at high risk for developing serious complications. This includes household contacts and caregivers of people with certain medical conditions including asthma, diabetes, and chronic lung disease.

Who should not get a flu shot?

The flu vaccine should not be given to:

  • Children younger than 6 months of age
  • People with severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine. This might include gelatin, antibiotics, or other ingredients.

Certain individuals should not be vaccinated without first consulting a healthcare professional. These patients include:

  • Those who have an allergy to eggs or any of the ingredients in the vaccine
  • Those who had Guillain-Barré Syndrome (a severe paralyzing illness, also called GBS) within six weeks of getting the flu vaccine previously
  • Those who have a moderate or severe illness with a fever should wait until they recover before getting a flu shot

What are the common side effects of the flu shot?

The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. Some minor side effects that could occur are:

  • Soreness, redness, or swelling where the shot was given
  • Fever (low grade)
  • Aches

If these side effects occur, they begin soon after the shot and usually last 1 to 2 days. Over the counter products may be recommended to manage minor side effects. Most people who receive influenza vaccine have no serious problems from it.

When is the best time to get a flu shot?

The CDC recommends that people get the flu shot as soon as vaccine becomes available and before the flu is widespread. The peak season is typically October to March in the U.S. but can start earlier or end later. As long as the virus is circulating, the flu shot should be received. A persons should get their flu shot every flu season to ensure the best protection from the flu.

*The flu shot is seasonally available:

At Healthcare Clinic for patients 2 years of age and over.
At Walgreens Pharmacy. Ages vary by state.

Check vaccine availability and schedule an appointment at a location nearest you.

If you believe you have a medical emergency,  please call 911.

Call the Centers for Disease Control and Prevention (CDC) at 800-232-4636 or visit www.cdc.gov/vaccines for more vaccine information.


Centers for Disease Control and Prevention (CDC). Seasonal Flu: Preventative Steps. November 13, 2018. https://www.cdc.gov/flu/consumer/prevention.htm. Accessed July 2019.

Hamborsky J, Kroger A, Wolfe S, eds. Centers for Disease Control and Prevention (CDC).Epidemiology and Prevention of Vaccine-Preventable Diseases. 13th ed. Washington, DC: Public Health Foundation, 2015.

Vaccine Information Statement: Influenza Vaccine (Inactivated). Centers for Disease Control and Prevention (CDC). August 7, 2015. http://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.pdf. Accessed July 2019.

Vaccine Information Statement: Influenza Vaccine (Live, Intranasal). Centers for Disease Control and Prevention (CDC). August 7, 2015. http://www.cdc.gov/vaccines/hcp/vis/vis-statements/flulive.pdf. Accessed July 2019.

Patient care services at Healthcare Clinic at select Walgreens provided by independently owned professional corporations including Take Care Health Services or local health system providers whose licensed healthcare professionals are not employed by or are agents of Walgreen Co. Walgreen Co. and its subsidiary companies provide management services to provider services, in-store clinics and worksite health and wellness centers. Privacy Practices

This publication should be used for general educational purposes only and is not intended to be a substitute for professional medical advice. Although it is intended to be accurate, neither Walgreen Co., its subsidiaries or affiliates, nor any other party assumes liability for loss or damage due to reliance on this publication.

* Vaccines subject to availability. State-, age- and health-related restrictions may apply.